A drainage basin is the area of land that drains water to a common outlet such as a river or lake. It is delimited from adjacent basins by a watershed divide. A drainage basin can be modeled as an open system with inputs like solar energy and precipitation, stores like glaciers, lakes, soil and vegetation that hold water, and outputs like evaporation and river discharge that remove water from the system. Water and energy from outside sources enter the basin and water leaves through various transfers and outputs.

1. Drainage Basins
Year 12 geography GCE

2. What is a drainage basin?
A drainage basin is the catchment area from which a river system obtains its
water. An imaginary line called the watershed delimits one drainage basin from
another.

3. How can we show the functions of a
drainage basin?
A drainage basin system can also be presented by a systems or flow diagram – as
shown below.

4. Why is a drainage basin an open system?
The drainage basin hydrological cycle is an open system with inputs and outputs.
Water and energy from the sun are introduced into the drainage basin from
outside and water can be lost from the drainage basin in a number of ways; such
as evaporation and river discharge into the sea.

5. What are inputs, stores, transfers and outputs?
Inputs include energy from the sun for to allow evaporation to occur and
precipitation to enter the system.
Stores include the obvious one such as glaciers, lake and puddles and less
obvious ones such as vegetation. Vegetation stores water that has been
intercepted or has been taken up by there roots form soil storage. Other
underground stores are soil storage and groundwater storage, (within rocks).
Transfers move water through the system and enable inputs of water to be
processed from one store to another. Transfers include thoughflow, stemflow,
infiltration, throughflow, and groundwater flow.
Outputs move water out of the drainage basin and include evaporation,
transpiration and river channel runoff into the sea.